1. (Technical Field)
The present disclosure relates to an apparatus for controlling a rotating machine based on an output signal of a resolver.
2. (Description of the Related Art)
Conventionally, a motor control system provided with a resolver and a resolver digital converter (hereinafter is referred to RD converter) is known. In the motor control system, a control apparatus controls a rotating machine based on the output signal of the resolver. Specifically, the control apparatus controls, based on the output signal of the resolver, a switching element included in the DC (direct current)-AC (alternating current) conversion circuit which is electrically connected to the rotating machine. For example, a Japanese Patent No. 5148394 discloses a motor control system provided with a resolver that generates a modulated wave in which an excitation signal is modulated by an amplitude-modulation based on the rotational angle of the motor, and a RD converter that calculates/outputs a calculated value of the rotational angle based on the detection of the generated modulated wave and the excitation signal.
In developing the motor control system, the inventors faced a problem that an accuracy of calculating the rotational angle outputted by the RD converter decreases when controlling the switching element in the DC-AC conversion circuit connected to the rotating machine to be ON and OFF thereby increasing the current flowing into the rotating machine. Therefore, there is a concern that the controllability of the rotating machine is decreased when the calculation accuracy of the rotational angle decreases.